Funds were requested for travel, and room and board for speakers and session moderators at the 39th Gordon Conference on Cancer, August 19-23, 1985, at Colby-Sawyer College in New London, New Hampshire. The themes of the meeting were tumor heterogeneity and tumor progression, and the genetic and epigenetic factors that play a role in the expression of these phenomena. Related topics on differentiation, drug resistance and therapy were included. The topics were deliberately diverse in order to encourage the participation of cell biologists, pharmacologists, molecular biologists, clinicians, pharmacologists, immunologists and pathologists. The areas were diverse but interrelated, and provided a unifying theme throughout the meeting. The meeting format was designed to achieve these goals by maximizing discussion. There were about 150 attendees drawn from academic, clinical, industrial, and governmental laboratories. There were only three morning and two evening speakers. Thirty minutes of discussion time followed each thirty minutes of presentation. The discussion leaders were prepared to offer constructive criticism, comparison with related work, and analysis of implications. A poster session, on-campus housing and dining, and free afternoons in a scenic but isolated setting fostered further exchange. (T)